对地球潮汐形变的观测与研究是了解地球内部结构的重要依据，也是大地测量学的基础研究课题。受观测资料的精度、空间分辨率和对地球内部结构参数不敏感等因素制约，传统大地测量手段（如重力仪、倾斜仪和应变仪等）在研究地球内部结构方面均未获实质性突破。我们的最新研究表明，全球定位系统（GPS）观测技术能提供水平精度达0.1mm和垂直精度达0.3mm的三维地球潮汐位移场，这为深入了解地球内部结构提供了契机。同时，GPS观测具有空间分辨率高、对观测环境要求低和成本低廉等优势，在研究地球内部结构方面极具潜力。本项目首次尝试利用全球三维GPS潮汐位移观测资料，建立和发展利用GPS潮汐观测数据反演地球深内部（固体潮部分）和上地幔（海潮负荷部分）的理论与方法。本项目的研究不仅对认识地球深内部和上地幔结构具有重要的科学意义，而且可为全球大地测量提供精化的潮汐位移改正模型。

Observation and investigation of tidal deformation, which is an important research topic in Geodesy, will provide new insights into Earth’s interior structure. Previous attempts to infer interior structure using conventional tidal observations from instruments such as gravimeters, strainmeters and tiltmeters have been largely unsuccessful because of limitations in accuracy, sensitivity and spatial coverage. Our latest study shows that Global Positioning System (GPS) can provide 3-D tidal displacement field accurate to the level of 0.1 mm (horizontal) and 0.3 mm (vertical), providing an opportunity to understand the physical structure of Earth’s interior. Furthermore, GPS observation with its low environmental impact, low cost, ever-increasing accuracy and resolution is poised to augment this knowledge by providing independent constraints on Earth’s interior structure. This project proposes to develop the theory and method of inferring the properties in the Earth’s deep interior (by body tide modeling) and the crust and uppermost mantle structure (by ocean tidal loading modeling) using observations from GPS tidal displacements. The project will not only provide important constraints to the structure of Earth’s interior, but also refine tidal displacement models for global geodetic research.